If you have played it fully and have gotten all the mechanics down pat, it should be pretty obvious why it’s not a fully digital game. The whole point of it is it to explore how you can communicate across mechanics with a static image with no feedback that a typical interactive medium would give. That’s why it has the name ‘0PLAYER’ in the first place. If it wasn’t that, you wouldn’t be able to praise it for teaching the internal logic the way it does. You can’t have both, it’s intrinsic to the format.
0.5player effectively takes the rule discovery aspect out of it, which is why it’s emphasised that it’s full of spoilers as it lays out what is actually happening fully and makes it a matter of just solving the puzzles you see rather than solving the how of that. So it should be really clear with that version why it isn’t intended to be interactive.
You also can very much just draw on the image, there’s nothing forcing you to have to edit the image to make it match the state that you want.